Such a communications network termination housing conventionally has sidewalls covering the electric assemblies but leaving the front end of the chassis modules uncovered.
It is desirable to add further plug-in units to such housings so that they can form, e.g., the termination of a communications network to which private branch exchanges of different sizes are connected. Prior-art housings which can be equipped with a different number of plug-in units are described in the special issue of `Telecom Report 10`, "Multiplex- und Leitungseinrichtungen" (1987), page 204. The dimensions of the housing itself, however, are invariable, so that it may be too large in some cases and too small in others. Housings for electric assemblies are also known which are designed as an add-on system to which further chassis modules can be added, if required. See for instance published German Utility Model (DE-GM 76 13 268.8). However, such housings are hard to protect against access by unauthorized persons. In addition, each individual housing has to be removed to allow access to the assemblies contained therein.